Heretofore, hypodermic medicinal injections or implantations into a patient frequently have been administered by the use of a hypodermic injector device comprised of a relatively thin barrel member of molded plastic or the like provided with a small diameter passageway through which a cylindrical pellet of a selected medicament may be forced into and through the hollow interior of an implanted hypodermic needle on one end of the barrel member by the thrust of a push rod on a separate plunger member inserted into the other end of the barrel. Both the barrel member and plunger member of such prior hypodermic injector devices are generally comprised of two or more individual component parts which must be separately fabricated and preassembled to form the completed members. As a result, the manufacture of such prior type hypodermic injector devices has been rather time-consuming and comparatively expensive.
In addition, such prior type hypodermic injector devices have been limited in the number of different injection and/or implantation usages for which they are adapted. Thus, they have not been capable of use with conventional hypodermic syringes such as hypodermic injection cartridges containing a predetermined filling of a liquid medicament, to effect the injection of either all, or only selected amounts of, the total medicament in the syringe or cartridge. Nor have such prior type hypodermic injector devices been capable of performing the subcutaneous implantation into a patient of thin electrodes with a trailing electrical conductor wire, such as are commonly employed for muscle stimulation purposes.